Prism



JbUl bll HUUIH June 7, 1938. 0. K. KASPEREIT PRISM Filed March 22, 1937Fig-5- mm m PM r V5. D nanfl u K Patented June 7, 1938 UNITED STATESQCZNL'H TKUUHi PATENT OFFICE 1 Claim.

(Granted under the act of March 3, 1883, as amended April 30, 1928; 3700. G. 757) The invention described herein may be manufactured and usedby or for the Government for governmental purposes, without the paymentto me of any royalty thereon.

This invention relates to a prism.

The purpose of the invention is to provide a one-piece prism designed todeviate the line of sight through an angle of 90 in the horizontal planeand through an angle of 45 in the vertical plane and to invert andrevert the image.

A practical embodiment of the invention is illustrated in theaccompanying drawing, in which Fig. 1 is a plan view,

Fig. 2 is a view in rear elevation,

Fig. 3 is a view in end elevation.

Referring to the drawing by characters of reference, the angles of alphaare equal to 67 30 and the angle beta is equal to 45.

The prism consists of a single block having parallel front and rearfaces respectively 5 and 6. Only a portion of the front face 5 isemployed as an entrant face 5 and opposite this portion is a reflectingface 1 making an angle of 45 therewith. The left end portion of theprism therefore constitutes a right-angle reflecting prism whose bottomface 8 is disposed horizontally. The prism has an inclined reflectingface 9 disposed in the path of the rays reflected by the face I and atan angle of 67 30' to the vertical line of the prism as indicated by theangle alpha in Fig. 2. The right end of the prism forms an emergent faceI at an angle of 67 30' to the reflecting face 9 and perpendicular tothe path of the rays reflected by the face 9. The upper face ll of theprism is a plane continuous surface.

The rays of light entering the prism at the face are deviated by thereflecting face 1 through an angle of 90 in the horizontal plane and aredirected onto the face 9 which deviates them through an angle of 45 inthe vertical plane. An inspection of the horizontal rays a, b, c, andthe vertical rays 0., b, e, shows that the image will appear invertedand reverted in the emergent face I0.

I claim:

A single prism for inverting and reverting an image embodying an entrantface for rays of light, a first reflecting face disposed at an angle of45 to the entrant face for deviating the rays of light through 90, asecond reflecting face making an angle of 67 30 with a planeperpendicular to the path of the rays deviated by the first reflectingface and receiving the rays of light from the first reflecting face anddeviating them through an angle of 45 to the plane perpendicular to thepath of the reflected rays and an emergent face making an angle of 6730' with the second reflecting face.

OTTO K. KASPEREIT.

